It might be a very useful feature for "special usage". I believe many current color sensors have this kind of subpixel structure (quad bayer) so it is not limited just to IMX294CJK. It is not required that it is made into an official binning mode - just a special Cap switch and raw data without debayering in the output.
By the way, it is not exactly accurate that it cannot be debayered. Many modern smartphones do that. It is just that common algorithms were not written for this. Look at the picture below. The boxes superimposed on subpixel structure. A very basic demosaicing algorithm will produce an RGB image with 2x resolution
And something like HQLinear can also be implemented for this structure (just needs some experimenting):
